Spanish Stem-Changing Verbs Practice

Q: What is a stem-changing verb in Spanish?

It's a verb whose stem vowel changes in the present tense whenever the stress falls on it: e→ie (querer → quiero), o→ue (poder → puedo), e→i (pedir → pido), plus u→ue for jugar (juego). The endings stay completely regular — only the vowel inside the stem moves.

Q: What is the boot (or shoe) pattern?

Write the six present-tense forms in a grid and draw a line around the forms that change — yo, tú, él/ella/usted and ellos/ellas/ustedes. The shape looks like a boot. Nosotros and vosotros sit outside the boot and keep the original stem: quiero, quieres, quiere, queremos, queréis, quieren.

Q: Why don't nosotros and vosotros change the stem?

Because in those forms the stress falls on the ending, not the stem: que-RE-mos, que-RÉIS. The vowel only changes when it carries the stress, so the unstressed stem stays intact. That's why quieremos and puedéis are always wrong.

Q: How do I know if a verb is e→ie or e→i?

You memorize it, but there's a shortcut: e→i verbs are always -ir verbs — pedir, servir, repetir, seguir, vestir. Common e→ie verbs include querer, pensar, empezar, cerrar, entender, preferir and sentir. When in doubt, contrast pedir → pido with preferir → prefiero.

Q: Do stem changes happen outside the present tense?

For -ar and -er verbs, no — volver gives volviendo and volvió with no change. But -ir stem changers also shift in the gerund (durmiendo, pidiendo, sintiendo) and in the third-person preterite (durmió, pidió, prefirió). These exercises drill both traps.

Q: Are these exercises free?

Yes. All 30 exercises run right in your browser, need no signup, and give you a clear explanation after every answer.

Question 1

Yo ___ ir al cine esta noche.

Accepted Answer

quiero. Querer is an e→ie verb: the stressed e opens to ie in the yo form, so it's quiero. "Quero" forgets the stem change.

Question 2

¿Qué ___ tú de esta idea?

Accepted Answer

piensas. Pensar changes e→ie in the tú form: piensas. "Pensas" keeps the old vowel, which only survives in nosotros and vosotros.

Question 3

La película ___ a las nueve y media.

Accepted Answer

empieza. Empezar is e→ie, and la película is a singular third-person subject, so it's empieza. "Empeza" misses the stem change.

Question 4

Las tiendas ___ a las ocho en mi barrio.

Accepted Answer

cierran. Las tiendas is plural, and ellos/ellas sits inside the boot, so cerrar changes e→ie: cierran, not "cerran."

Question 5

No ___ esta pregunta del examen. (yo)

Accepted Answer

entiendo. Entender changes e→ie in the yo form: entiendo. "Entendo" treats the verb as regular — the classic beginner trap.

Question 6

Mi hermana ___ el té al café.

Accepted Answer

prefiere. Preferir is e→ie, and mi hermana is third-person singular, so it's prefiere. Note that only the second e changes — the one that carries the stress.

Question 7

¿___ ayudarme con los deberes? (tú)

Accepted Answer

Puedes. Poder changes o→ue in the tú form: puedes. "Podes" keeps the original o, which only nosotros and vosotros do.

Question 8

El bebé ___ diez horas cada noche.

Accepted Answer

duerme. Dormir is o→ue, and el bebé is third-person singular, so it's duerme. "Dorme" forgets the stem change.

Question 9

Yo ___ a casa a las seis de la tarde.

Accepted Answer

vuelvo. Volver changes o→ue in the yo form: vuelvo. "Volvo" is a car, not a verb form — the stressed o must open to ue.

Question 10

Mi abuelo siempre ___ historias de su pueblo.

Accepted Answer

cuenta. Contar is o→ue and mi abuelo is third-person singular, so it's cuenta. "Cuentan" would need a plural subject.

Question 11

No ___ mis llaves por ninguna parte. (yo)

Accepted Answer

encuentro. Encontrar changes o→ue in the yo form: encuentro. "Encontro" treats the verb as regular and misses the change.

Question 12

Los niños ___ en el parque después de clase.

Accepted Answer

juegan. Jugar is the only u→ue verb in Spanish: juego, juegas, juegan. "Jugan" keeps the u, which only happens in jugamos and jugáis.

Question 13

Yo siempre ___ paella en este restaurante.

Accepted Answer

pido. Pedir is an e→i verb: the e drops straight to i, giving pido. "Piedo" wrongly applies the e→ie change — pedir never takes ie.

Question 14

Este bar ___ tapas hasta medianoche.

Accepted Answer

sirve. Servir is e→i, so the third person is sirve. "Sierve" is the trap — servir belongs to the e→i group, not e→ie.

Question 15

El profesor ___ la pregunta dos veces.

Accepted Answer

repite. Repetir is e→i: repite. Only the second e — the stressed one — changes; "repiete" wrongly turns it into ie.

Question 16

Yo ___ las instrucciones de la receta paso a paso.

Accepted Answer

sigo. Seguir is e→i and also adjusts its spelling: the gu becomes g before o, giving sigo. "Siguo" keeps the u where it isn't needed.

Question 17

Mi hijo ya se ___ solo por las mañanas.

Accepted Answer

viste. Vestirse is an e→i verb: se viste. "Veste" misses the change, and "visto" is the participle of ver, not a present-tense form here.

Question 18

Ella ___ en la oficina casi todos los días.

Accepted Answer

almuerza. Almorzar is o→ue, and ella is third-person singular: almuerza. "Almorza" keeps the o, which only nosotros and vosotros do.

Question 19

In the present tense, which forms of a stem-changing verb like poder keep the original stem?

Accepted Answer

nosotros and vosotros. Only nosotros and vosotros keep the stem, because the stress falls on the ending instead of the stem: podemos, podéis. Every other form changes — that's the boot.

Question 20

Nosotros ___ a casa en tren todos los viernes.

Accepted Answer

volvemos. Nosotros sits outside the boot, so the stem does NOT change: volvemos. "Vuelvemos" applies the o→ue change where it never belongs.

Question 21

¿A qué hora ___ vosotros la tienda?

Accepted Answer

cerráis. Vosotros is outside the boot, so cerrar keeps its e: cerráis. "Cierráis" is the trap — the stem change never reaches vosotros.

Question 22

¿___ venir a la fiesta el sábado? (vosotros)

Accepted Answer

Podéis. Vosotros keeps the original stem: podéis. "Puedéis" wrongly drags the o→ue change outside the boot.

Question 23

Which sentence has a boot-pattern error?

Accepted Answer

Nosotros quieremos ir a la playa.. "Quieremos" is wrong because nosotros sits outside the boot and keeps the plain stem: queremos. The change belongs to the other four forms.

Question 24

Ellos siempre ___ dos cafés con leche.

Accepted Answer

piden. Pedir belongs to the e→i group, so the e drops to i: piden. "Pieden" is the classic trap of applying e→ie to an e→i verb.

Question 25

Choose the correct pair: "Yo ___ el vino tinto, pero él siempre ___ cerveza." (preferir / pedir)

Accepted Answer

prefiero / pide. Preferir is an e→ie verb (prefiero) while pedir is e→i (pide). Mixing up the two groups is the most common stem-change mistake.

Question 26

El niño está ___ la siesta en su habitación.

Accepted Answer

durmiendo. -ir stem changers shift o→u in the gerund: durmiendo. "Duermiendo" wrongly applies the boot change, and "dormido" is the past participle.

Question 27

Últimamente me estoy ___ muy cansado.

Accepted Answer

sintiendo. Sentir is an -ir stem changer, so its gerund takes e→i: sintiendo. "Sientiendo" wrongly uses the boot change ie, which never appears in the gerund.

Question 28

Anoche el niño ___ doce horas seguidas.

Accepted Answer

durmió. In the preterite, -ir stem changers shift in the third person: dormir → durmió (o→u). "Dormió" misses the change and "dormí" is the yo form.

Question 29

Ella ___ la cuenta y pagó con tarjeta.

Accepted Answer

pidió. Pedir changes e→i in the third-person preterite: pidió. "Pedió" forgets the change — it only happens in él/ella and ellos/ellas (pidió, pidieron).

Question 30

Which sentence has a stem-change error?

Accepted Answer

El bebé está dormiendo tranquilamente.. "Dormiendo" is wrong: -ir stem changers shift o→u in the gerund, so it must be durmiendo. The other three apply the -ir changes correctly.

Spanish Stem-Changing Verbs Practice

The rule, in plain English.

Practice.

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Present Tense Practice

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